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Re: bad estimation together with large work_mem generates terrible slow hash joins - Mailing list pgsql-hackers

From Robert Haas
Subject Re: bad estimation together with large work_mem generates terrible slow hash joins
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Msg-id CA+TgmoYt9gtGc+-oCprBV7OKwAvTwK24ZF_G7ZHrFq6VnsSAwg@mail.gmail.com
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In response to Re: bad estimation together with large work_mem generates terrible slow hash joins  (Tomas Vondra <tv@fuzzy.cz>)
Responses Re: bad estimation together with large work_mem generates terrible slow hash joins  (Robert Haas <robertmhaas@gmail.com>)
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On Thu, Sep 11, 2014 at 5:57 PM, Tomas Vondra <tv@fuzzy.cz> wrote:
> Attached is the patch split as suggested:
>
> (a) hashjoin-nbuckets-v14a-size.patch
>
>     * NTUP_PER_BUCKET=1
>     * counting buckets towards work_mem
>     * changes in ExecChooseHashTableSize (due to the other changes)

OK, I'm going to work on this one now.  I have some ideas about how to
simplify this a bit and will post an update in a few hours once I see
how that pans out.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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